1. Field of the Invention
Embodiments of the present invention relate generally to a fuel leak prevention system, and more particularly to a system to prevent fuel from leaking or dripping from the dispensing end of a fuel nozzle after the nozzle has been deactivated.
2. Description of Related Art
Fuel dispensing nozzles of the general type used on fuel pumps in fueling stations are well understood in the art. These nozzles are normally provided with hold-open catches for holding an operating lever in an open position, and are provided with an automatic shut-off means for shutting off the flow of fuel from the nozzle when the tank level reaches the discharge end of the nozzle. The hold-open catch feature and the automatic shut-off means allow the operator to leave the nozzle unattended during the filling operation without fear that the tank will overflow should it become full while the nozzle is unattended.
The fuel nozzle generally works off of pressure created by the flow of fuel from the pump. When the hold-open latch is engaged, the poppet valve stem is open, allowing fuel to flow. As the fuel flows, the anti-drain valve in the spout is open, which sucks air into a vacuum chamber above the poppet valve.
As long as the vacuum chamber is in equilibrium with the atmospheric pressure beneath the diaphragm of the chamber, the poppet is engaged, and the flow of fuel will continue. When either the hold-open latch is disengaged, or when the anti-drain valve is covered by fuel (full tank) air intake ceases, and the poppet valve stem closes, disrupting the flow of fuel.
Since the point of closure is in the handle of the nozzle, there is an area between the poppet and the end of the spout where fuel may remain after fueling. Depending on the length, the diameter, and the curvature of the spout, the fuel retained in this area can vary from a few drops to several ounces. Thus, fueling nozzles retain fluid between the shut-off mechanism and the end of the spout.
This uncontained fuel can be spilled on the car, ground, or on the body, creating a fire, clean-up, and environmental hazard. In such a nozzle, it is sometimes desirable to provide for a shut-off valve at the tip of the nozzle spout and in the fuel supply passage to avoid drips from the spout after the nozzle is removed from the fill tube of a fuel tank of the motor vehicle, as there is ever increasing concern about damage to the environment resulting from the contamination of ground water and soil due to spillage of vehicle fuels, petroleum substances and other chemicals. Part of the damage is caused by the dripping of excess liquid from the nozzle used to dispense the fuel or liquid, after the nozzle has been deactivated. As described, in general, once the nozzle is deactivated, there remains a small amount of excess liquid in the nozzle. As the nozzle is removed from the fuel tank or container, the remaining liquid tends to drip from the dispensing end of the nozzle onto the surrounding ground surface or onto the user. In addition, part of the damage is caused by activation of the nozzle when the nozzle is removed from the container or fuel tank. Activation of a nozzle outside of a container or fuel tank also presents a safety problem due to the spillage of the flammable fuel.
Fueling stations rely on consumers to dispense fuel. A typical nozzle is handled hundreds of times a day. Spillage from the spout is normal. The wasted fuel may eventually enter a storm drain through run off and cleaning procedures. Fuel seeping into the ground contaminates soil, streams, rivers, lakes, and drinking water. For example, one quart of spilled fuel can contaminate 250,000 gallons of fresh drinking water. One pint of fuel seeping into a lake can create a one acre slick, preventing the replenishment of oxygen, blocking sunlight, and impairing photosynthetic processes.
Spilled fuel also releases Volatile Organic Compounds (VOC's) that have long and short term adverse health effects. VOC's are organic chemical compounds that have high enough vapor pressure under normal conditions to significantly vaporize and enter the atmosphere. These vapors contribute to air pollution and greenhouse gases.
The cost of fuel is also a consideration to retain spillage. At US$4.00 per gallon, one ounce of fuel costs US$0.03. Over many spills, this can amount to a large amount of fuel inventory lost. There is also, of course, the considerable inconvenience and potential safety hazards this problem poses to the consumer, including the risk of spillage or drippage onto clothes, shoes, or hands, not to mention the safety hazards posed by drippage of fuel onto the driveways at fueling stations.
To help prevent spillage of the liquid, a non-drip assembly is needed to prevent the excess liquid from dripping from the end of the nozzle once the nozzle has been deactivated. The related art has shown various apparatus for preventing a liquid dispensing nozzle from dripping liquid after the nozzle has been deactivated. Illustrative are U.S. Pat. No. 4,014,472 to Bennett; U.S. Pat. No. 4,213,488 to Pyle; and U.S. Pat. No. 5,377,729 to Reep.
Bennett describes a nozzle assembly for high speed filling units. The nozzle assembly includes an upper casing within which is mounted a nozzle piston structure. The piston structure is fastened to an inner, hollow sleeve member to move the sleeve member. The sleeve member is provided with openings adjacent the piston structure to allow for communication between the inner space of the hollow sleeve member and the cylinder space. The end of the inner sleeve member opposite the piston structure is provided with discharge openings and a plug-like end closure member. A spring mounted around the inner sleeve member acts to bias the sleeve into the closed position. An outer sleeve member is slidably mounted around the inner sleeve member and is fixably secured to the lower casing of the nozzle assembly. In operation, the pressure of the fluid causes the piston to open which in turn moves the inner sleeve member outward thus, moving the end of the inner sleeve member beyond the outer sleeve member which exposes the discharge openings. Once the flow of fluid stops, the spring biases the piston structure and the inner sleeve member into the closed position.
Pyle describes a valve located in the end of a nozzle for preventing the flow of fuel and fuel vapors out of the nozzle when the nozzle is deactivated. In one embodiment, a pinch valve is located at the end of the nozzle. The pinch valve comprises a resilient sleeve and is designed to open and close by the action of air or hydraulic pressure acting on the resilient sleeve. A fluid passageway is provided to establish communication between the pinch valve and the flow passage upstream of the flow control valve. When the nozzle is deactivated, the pinch valve is in fluid contact with the flow passage such that the pressure from the fluid flowing to the pinch valve acts to close the pinch valve. When the nozzle is activated, a passageway is formed between the fluid passageway and the flow passage downstream of the flow control valve such that the fluid flows out of the fluid passage and the pinch valve and out of the flow passage. In another embodiment, a wafer valve is mounted in the end of the nozzle and acts to seal the end of the nozzle. The wafer valve comprises two substantially semi-circular discs pivotally arranged around a shaft which extends from one side of the end of the nozzle to the other to support the discs. The wafer valve uses a similar construction as described above to open and close.
Reep describes a check valve device for a fuel pump nozzle. The device includes a stopper having a stem mounted on a plug member. The plug member is sized to close the dispensing end of the nozzle. A support member is mounted on the stem of the stopper to guide and support the stopper. The support member has two extension members mounted in an essentially U-shaped manner. The extensions engage the inside wall of the nozzle to hold the support member securely within the passage. The support member is shaped to allow the fuel to pass through the nozzle. A spring is mounted between the end of the stem opposite the plug member and the support member. The spring acts to bias the stopper back into engagement with the end of the nozzle. In operation, the plug member is seated within the end of the nozzle when fuel is not being dispensed. Once the fuel pump is activated, the fuel pressure on the plug member acts to move the plug member out of engagement with the end of the nozzle. Once the pump is deactivated, the force acting to disengage the plug member is less than the force of the spring acting to move the plug member back into engagement with the end of the nozzle. Consequently, the plug member acts to close the end of the nozzle such as to prevent the nozzle from dripping.
Also of some interest are U.S. Pat. No. 3,324,904 to Crotners; U.S. Pat. No. 4,749,010 to Petell; and U.S. Pat. No. 4,834,151; and U.S. Pat. No. 5,249,611 all to Law which show non-drip apparatus which are activated by removal of the nozzle from contact with the container.
Further, of interest are U.S. Pat. No. 2,936,799 to Mannon; U.S. Pat. No. 3,521,679 to Copony; U.S. Pat. No. 3,994,323 to Takahata et al. and U.S. Pat. No. 5,076,333 to Law which show the closing off of the venturi opening or the air vent tube in response to removal of the nozzle from the container or fuel tank which stops the flow of liquid in the nozzle.
There remains a need for a liquid dispensing nozzle that will not drip excess liquid once the nozzle is deactivated. What is needed is a system of isolating any remaining liquid between the poppet stem valve and the terminal end of the spout, in order to retain any remaining liquid in the nozzle, and eliminate leakage. It is to such a system that the present invention is primarily directed.